U.S. Pat. No. 4,855,219 issued to Bagchi et al. and U.S. Pat. No. 4,920,004 issued to Bagchi described strongly adhering matte bead particles for photographic systems having a polymeric core covalently bonded to a gelatin shell. These particles are referred to as gelatin grafted polymer particles (gel-g polymer particles).
Soft polymer latex particles covalently bonded to gelatin particles, the preparation thereof and their use as materials that can be incorporated in photographic layers to reduce the pressure sensitivity of various photographic products are extensively described in U.S. Pat. Nos. 5,026,632 and 5,066,572. The particles are described as gelatin-grafted soft latex particles (gel-g soft latex particles) which when subjected to a subsequent crosslinking produces a soft core surrounded by a shell of cross-linked gelatin and referred to as case hardened gel-grafted soft latex particles (CH gel-g latex particles). Thus, the term gel-g particles refers to both described types of particles covalently bonded to a shell of gelatin.
Even though in many cases photographic layers comprising gel-g-latexes or case-hardened gel-g-latexes can be coated without any difficulty or product defects many times, defects due to aggregation or flocculation involving the gel-g-latexes or case-hardened gel-g-latex particle have been seen in fabricated photographic coatings. This is a serious disadvantage for the formulation of photographic products with layers comprising gel-g-latex or case-hardened gel-g-latexes.